Olefin extrusion compositions and method of preparing same

ABSTRACT

A fluorochemical, perfluorocyclohexanoyl glycine, is blended at low concentrations with olefin polymers to obtain an extrudable composition having advantageous repellency characteristics.

0 United States Patent 1151 3,674,757 Uffner 1 July 4, 1972 154 OLEFINEXTRUSION COMPOSITIONS [56] References Cited AND METHOD OF PREPARINGSAME UNITED STATES PATENTS 72] t2 MlllW.Uft ,Md ,P. 1 or e e e a3,382,097 5/l968 Erby ct al. ..117/141 [73] Assignee: Air Products andChemicals, Inc.,

Philadelphia, Primary ExamirrerJoseph L. Schofer l 17 0 AssistantExaminer-Edward J. Smith [22] ed y Attorney-B. Max Klevit and David T.Nikaido 211 App]. No.: 55,990

[57] ABSTRACT UeSe Cl- R, A fluorochemical perfluorocyclohexanoylglycine blgnded 260/8811260/937, GB at low concentrations with olefinpolymers to obtain an ex- [5 1] Int. Cl. ..C08f 29/04 tmdabh compositionhaving advantageous repellency h 53 Field of Search ..260/88.2, 937,949GD, 94.9 GB; mimic,

9 Claims, No Drawings OLEFIN EXTRUSION COMPOSITIONS AND METHOD OFPREPARING SAME BACKGROUND. OF THE INVENTION The present inventionrelates to extrudable compositions prepared by blending a fluorochemicalat low concentrations with olefin polymers and more particularly, toimparting repellency characteristics to extrudable compositions byblending perfluorocyclohexanoyl glycine at low concentrations witholefin polymers which are to be extruded.

Olefin polymers, such as polyethylene, are used extensively in food andindustrial packaging applications, particularly in the form of coatingson paper, paper board; cellophane and other plastic films; metal foil;cloth; and other substrates. The main contributions ,of these coatingsinclude a heat-sealable surface, increased tear and crease resistance,and a moisture barrier. Such olefin polymers, however, have theseriousdrawback of being permeable to oils and greases. In order toincrease the oleophobicity of the olefin polymers it has been necessaryto subject the polymers to some form of surface treatment, such asovercoating the surface with polyvinylidene chloride. Surface treatmentsentail at least one additional processing step and normally require thepresence of driers to flash ofi the water or solvent which is used as avehicle during the surface treatment operation.

SUMMARY OF THE INVENTION An object of the present invention is toprovide an extrudable olefin composition having advantageous repellencycharacteristics.

Another object of the present invention is to provide an olefincomposition which can be extruded or blown and which has a high degreeof imperviousness to oils and greases.

Still another object of the present invention is to provide a uniqueblend of fluorochemical and olefin polymer which has greateroleophobicity than the olefin polymer alone.

These and further objects, advantages and features of the invention areobtained by physically blending a small quantity (0.1 to 5 percent byweight) of perfluorocyclohexanoyl glycine (C F,,CONHCH,CO H, melting inthe range of 128 to 134 C.) with the desired olefin polymer until ahomogeneous blend is obtained. Advantageously, this is done by blendingthe perfluorocyclohexanoyl glycine into a melt of the olefin polymer.The resulting blend can be extruded or blown in accordance with standardprocedures known in the art. Since the perfluorocyclohexanoyl glycinecan be blended with the olefin polymer at the same time other additives,such as antistats, lubricants, etc., are incorporated with the olefinpolymer and since such operations are normally done prior to extrusionor blowing, the need for a multiple coating station and costly driers iseliminated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment ofthe invention, the olefin polymer typically in the form of chunks orpowder is fed into a cell of a kneading-type blender, such as a sigmablade blender. The cell is then heated to the softening temperature ofthe olefin polymer. When the olefin polymer is completely melted theperfluorocyclohexanoyl glycine is added to the cell and the blending iscontinued at the same temperature until a uniform or homogenous blend ofthe fluorochemical and olefin polymer is efiectuated. Typically, celltemperatures in the neighborhood of 120 to 135 C. are employed; thetemperature being limited by such considerations as thermal degradationof the olefin polymer, the softening points of the olefin polymer andthe fluorochemical and other conditions for rapid and effectiveblending.

The resulting olefin polymer-fluorochemical blend can then be extrudedor blown. Normally, in extrusion operations the blend, after beingsubjected to heat and pressure inside a cylinder, is extruded throughthe narrow slit of an extrusion coating die. The slit is straightlined-shaped and the emerging hot film has the form of a thin sheet.Upon leaving the die, the

molten film is drawn down into the nip between the two rolls below thedie, viz., the driven, water-cooled chill roll and the rubber-coveredpressure roll. These two rolls are the center of the extrusion coatingprocess. Here, while coming into contact with the faster movingsubstrate, such as a plastic film or paper, the hot film is drawn out tothe desired thickness, or gauge, and forced onto the substrate when bothlayers are pressed together by the two rolls. The pressure is generallymaintained between to 100 pounds per linear inch. The combination ofsubstrate and extruded film is then rapidly cooled by the chill roll.

Obviously, good mixing of the heated olefin polymer is essential forobtaining a good coating with no defects or blemishes recognizable byeither the naked eye or testing tools. Among the defects which may beencountered because of poor mixing in conventional operations includepin holes, which make ordinary olefin polymer coatings permeable togrease, chemicals, moisture and vapor.

In addition to improving the oleophobicity of the olefin polymer, thefluorochemical employed herein improves the extrudability and release ofthe polymer from metal parts. It has also been observed that the heatstability of polyethylene, for example, is improved by the addition ofthe perfiuorocyclohexanoyl glycine.

Any olefin polymer, including polyolefins and olefin copolymers, whichmay be extruded or blown can be used as the olefin polymer in thepresent invention. Such polymers particularly include high density andlow density polyethylene, high and low density polypropylene,ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, such asethyleneethyl acrylate copolymer, ethylene-acrylic acid copolymer,propylene-methacrylic acid copolymer, and the like.

As indicated above, only small quantities of fluorochemical are requiredin order to impart the desired repellency characteristics to the olefinpolymers. In general, between 0.1 to 5 percent by weight of theperfluorocyclohexanoyl glycine is sufficient to obtain the desiredresults and preferably between 0.5 to 2 percent by weight of theperfluorocyclohexanoyl glycine is employed. The actual preparation ofthe perfiuorocyclohexanoyl glycine can be accomplished in accordancewith the following procedure:

grams of glycine, 400 milliters of water and 320 grams of sodiumhydroxide (50% solution) are added to a 2-liter flask equipped with a500 c.c. dropping funnel, mechanical stirrer and a condenser.Perfluorocyclohexanoyl fluoride (328 grams) is then added to thedropping funnel. The acid fluoride is added dropwise over a 3- /6 hourperiod to the stirred flask which is maintained at an internaltemperature of 10 C. Dark brown solids are formed during this reaction.The heterogeneous mixture is then allowed to stand at room temperatureover-night. The organic layer (which is the top layer) in the flask isseparated from the aqueous or bottom layer. The aqueous layer is thenextracted with diethyl ether and the other extracts are added to theorganic layer. The resulting organic layer is then acidified with excessaqueous hydrochloric acid and dried over magnesium sulfate. Dark brownsolids obtained during the process are recrystallized twice from benzeneto provide in low yield a light tan solid which is perfluorocyclohexanoyl glycine, melting at 128 to 134 C.

The effectiveness of the blends of fluorochemical and olefin polymer ofthe present invention is demonstrated in the following examples. It willbe understood that these examples are intended to be illustrative andare not intended to be limiting.

EXAMPLE I Perfluorocyclohexanoyl glycine was thoroughly blended withpolyethylene (melt index 22, density 0.915 and Vicat softeningtemperature of about 82 C.). It will be seen from the following tablethat the addition of small amounts of the fluorochemical dramaticallyincreased the oleophobicity of the control material, polyethylene. TAPPIT 507su-68 test, using peanut oil as the reagent, was employed todetermine Composition of film Peanut Oil Holdout 2 mils thick Hours at60C. PE 48 PE 0.75% FC 59 PE 1.00% FC 68 PE 2.00% FC 92 All of the filmswere heat sealable at from about 93 C. to about 99 C. on a Sentinel HeatSealer set at 30 psi for one second, dwell time, using a one-fourth inchbar. Therefore, the presence of the fluorochemical did not deleteriouslyaffect the inherent heat sealability of the polyethylene. What wasaccomplished was a dramatic increase in the oleophobicity of thepolyethylene composition.

The fluorochemical, perfluorocyclohexanoyl glycine, did impart a slighthaze to the polyethylene. This haze was not objectionable, however.

Although, ideally, extruded films and coating should be pin hole free,the presence of fluorochemical in the polyethylene imparts holdout evenif minute pin holes occur. This is because oil cannot wet and wickthrough the pinhole when it has a fiuorochemical surface exposed.

EXAMPLE ll Following the procedure of Example I, using U.S.l.sMicrothene FN-500 polyethylene, various fluorochemicals were thoroughlyblended by a sigma blade mixer with the polyethylene for about to 30minutes at 120 to 150 C. and then the mixture was pressed into film 5mils thick. The following average peanut oil holdout times wereobtained:

Composition of Film Peanut Oil Holdout 5 mils thick Hours at 60C. PE(control) 80.5 PE 1% FC 260 film thickness in commercial use usuallyranges from 0.5 to 5 mils. I

From the foregoing it will be seen that this invention is well adaptedto obtain all of the ends and objects hereinabove set forth, togetherwith other advantages which are obvious and which are inherent to thesystem. The oleophobicity of olefin polymers is dramatically improved bythe addition of small percentages of perfluorocyclohexanoyl glycine. Thecompositions resulting from blending the fluorochemical with the olefinpolymer not only have improved repellency characteristics, but alsoresult in improved extrudability and release from metal parts.

Obviously, many modifications and variations of the present invention ashereinbefore set forth may be made without departing from the spirit andscope thereof and therefore only such limitations should be imposed asare indicated in the appended claims.

What is claimed is:

l. A composition comprising from about 0.1 to about 5 percent by weightperfluorocyclohexanoyl glycine and a solid ex trudable olefin polymer.

2. The composition of claim 1 in which the perfluorocyclohexanoylglycine is present in the amount of between about 0.5 and 2 percent byweight.

3. The composition of claim 1 in which the olefin polymer is ahomopolymer.

4. The composition of claim 1 in which the olefin polymer is acopolymer.

5. The composition of claim 1 in which the olefin polymer ispolyethylene.

6. The composition of claim 1 in which the olefin polymer is an ethylenecopolymer.

7. The composition of claim 1 in which the olefin polymer ispolypropylene.

8. The process of producing oleophobic olefin polymers which comprises:

heating a solid extrudable olefin polymer to its softening temperature,

adding 0.1 to 5 percent by weight of perfluorocyclohexanoyl glycine tothe heated olefin polymer,

and mixing the perfluorocyclohexanoyl glycine and olefin polymer until auniform blend is obtained.

9. The process of claim 8 in which the perfluorocyclohexanoyl glycineand the olefin polymer are mixed at a temperature of to C. until ahomogenous blend is obtained.

2. The composition of claim 1 in which the perfluorocyclohexanoylglycine is present in the amount of between about 0.5 and 2 percent byweight.
 3. The composition of claim 1 in which the olefin polymer is ahomopolymer.
 4. The composition of claim 1 in which the olefin polymeris a copolymer.
 5. The composition of claim 1 in which the olefinpolymer is polyethylene.
 6. The composition of claim 1 in which theolefin polymer is an ethylene copolymer.
 7. The composition of claim 1in which the olefin polymer is polypropylene.
 8. The process ofproducing oleophobic olefin polymers which comprises: heating a solidextrudable olefin polymer to its softening temperature, adding 0.1 to 5percent by weight of perfluorocyclohexanoyl glycine to the heated olefinpolymer, and mixing the perfluorocyclohexanoyl glycine and olefinpolymer until a uniform blend is obtained.
 9. The process of claim 8 inwhich the perfluorocyclohexanoyl glycine and the olefin polymer aremixed at a temperature of 120* to 150* C. until a homogenous blend isobtained.